Before resolving damage, I must ask if a tapped blocker still deals damage -- I still don't understand the more recent (within the past 5 or so years) rules changes with combat. If I can do it, I will pay R to tap the Shaman to kill your Child of Night, thereby leaving you with only your Soliton (which would naturally deal 3 damage to me).

If I can't do that and still deal combat damage to the Unicorn, then I won't do that, because I'd like to kill the Unicorn.

So, Judge Mooseman, can I kill both and only feel the wrath of your Soliton?

Untap, upkeep, draw.
Bloodpyre Elemental (4/1; Elemental; Sacrifice ~: ~ deals 4 damage to target creature. Activate this ability only any time you could cast a sorcery.)
Sac it to kill the Bulvox.
Attack with all 3.
Done.